Vacuum tube



Jan. 1 1 192?.

M. WATROUS VACUUM TUBE Filed Nov. 25, 1919 Hiya /M van for Pau/ M 14/4/0045 Patented Jan. 11, 1927..

UNITED STATES PATENT OFFICE.

PAUL M. WATROUS, OF JERSEY CITY, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

VACUUM TUBE.

Application filed November 25, 1919. Serial No. 840,455.

This invention relates to vacuum tubes and has particular reference to electrodesupporting means forvacuum tubes.

An object of the invention is to provide an electrode-supporting means, the resiliency of which, to a minimum degree, is ati'e-eted by the heat normally generated in a vacuum tube, particularly when such a tube.

is a three electrode amplifier of currents or a transmitter of power.

Another object is to provide a resilient electrode-suspending element so constructed as to permit of the ready adjustment of the electrode and its constant maintenance under uniform tension'thereafter.

In general, tubes have thus far been provided in which an electrode, such as, for instance, the cathode, has been supported by means of a rigid link or member attached at one end to the electrode, and at the other end to a supporting member, such as a glass arbor or some other member of insulatmg material. On the other hand, supporting means have been provided in the form of bow-shaped springs or helical springs which were connected to the filament and to the support in a manner similar to that mentioned above. In the majority of these cases, however, the resilient supporting element has been located between the support and the electrode, and this location in most cases has been such that the resistant supporting element has been subjected, to a large degree, to the heat generated by the action between the clcctrodes. Furthermore, previous suspending n'ieans have not provided the ready and high degree of adjustment which this invention provides.

The electrode to be supported and which 10 is to be maintained under a uniform tension is connected atone of its ends to a link member which member passes through an aperture in an insulating plate and, beyond said aperture, is connected to the resilient supporting means. This resilient supporting means comprises two portions, one. portion of which functions-as a spring to subject the link to a constant and uni-directional force, and the other portion of which acts as a bearing for that portion of the link which passes through the insulating plate and thereby provides a smooth bearing for the same.

The invention is illustrated in the drawing of which Fig. 1 shows a perspective View LTI partially broken away, of a tube embodying the invention; arid Fig. 2 shows an enlarged detailed view of the invention.

As illustrated in the drawing, the invention comprises an evacuated vessel 1 having the usual stem 2, and press 3 through which suitable lead-in wires 4, 5, 6 and 7 extend. A collar 8 embraces the stem 2 and has upwardly extending arms 9 and 10 which, at their upper ends are welded, or otherwise suitably fastened, to an electrode 11 which is shown in the form of a cylindrical electrode of oval cross section, forming an anode. This anode may be formed of any suitable material, but preferably is formed of nickel. Along edges of the anode which lie in,

a plane at right angles to the plane of attachment of the members 9 and 10 thereto, are welded or suitably attached a pair of uprights 12 and 13 which, in the form shown, may be made of hollow tubing. This tubing may, along the edges of the contact with the anode 11, be flattened out. To the upper and lower ends of the uprights 12 and 13, are attached the plates of insulating material 14 and 15. This insulating material may be made, in one form, of lavite which is capable of ready machining and is suitable for use within vessels having a high degree of vacuum and in which the material is readily denuded of occluded gases. Within the anode 11 is symmetrically supported a control electrode 16 which, in the form shown, comprises a plurality of turns of wire in the form of a helix. This wire may be of nickel or other suitable material and is welded or otherwise suitably attached at a number of points of contact to a plurality of upright rods 17, 18, 19 and 20. These rods 17, 18, 19 and 20 are connected 95 at their upper and lower ends respectively in suitable apertures in plates 14 and 15.

symmetrically supported within the control electrode 16 is a filamentary cathode 21. This cathode 21, in the form shown, is Wt 300 shaped and preferably comprises a strip of platinum ribbon which has been twisted and coated with thermionically active material such as oxides of the alkaline earth metals. The upper ends of this filament 21 105 are supported by hooked portions of link members 22 and 23; the lower portions of the filament are connected to hooked portions of wires 24:, 25 and 26 which are suitably fastened to the lower plate member 15. The

lead-in wires 4, 5, 6 and 7 are connected in a suitable manner well known in the art, to the various electrodes whereby electrical circuit connections may properly be made to the vacuum tube.

The link members 22 and 23, the lower ends of which have hooked portions 27, extend upwardly through apertures 28 in the plate member 14 and at their upper ends are connected to coiled spring members 29. This connection is preferably made by welding the member 22 to the spring 29. The spring member 29 comprises two portions A and B. The portion A is of a diameter several times greater than the portion B, and is the portion which subjects the link member 22 to the proper amount of uni-directional force to maintain the filament 21 under a suitable tension. The portion B of the spring member 29 is wound in a coil of much smaller diameter than portion A and is so proportioned that its outside diameter permits it to be snugly inserted in aperture 28 in plate 14. In the operation of my invention it will be assumed that the various parts of the tube had been assembled with the exception of the filament. The filament is connected tothe supports 24, 25 and 26 and allowed to hang in free loops in the direction of the plate 14. One of the link members is passed through an aperture 28 to engage with the filament, after which the spring is placed in. the hole in the plate 14, and its portion 27 is engaged with one of the free loops of the filament. The other end of the link member is grasped by a suitable tool and the link member is moved to subject the filament to the required degree of tension. In this position the end of spring 29 is then welded to the link. The other link member isin an exactly similar man ner connected to its respective loop portion of the filament 21.

It will be noted, therefore, that this particular type of suspension element provides a smooth bearing for the link member supporting the filament so that the sliding friction of the link in the aperture is considerably reduced. It will also be noted that the portion of the suspension element which maintains the filament under tension is 10-- cated, for the purpose of preserving its resiliency, as far as possible, away from the zone of heat generated. within the tube. Furthermore the portion A of the spring member is definitely centered in its position by means and reason of itsintegral connection with portion B so that the link member 52, bemg connected to the portion A and passing through the portion B, is maintained more uniformly in its proper axial alignment whereby lateral vibrations of the filament are substantially avoided.

What is claimed is:

1. In an electron discharge device, a block of insulating material having an aperture, a suspension device comprising a tubular portion arranged in said aperture, a resilient member having one end connected to one end of said tubular portion, a rod slidably mounted in said tubular portion, said rod being connected at one end to the other end of said resilient member, a hook on the other end of said rod and a filamentary cathode supported by said hook.

2. In an electron discharge device, a block of insulating material having an aperture, a closely wound wire helix arranged in said aperture, .an open wound wire helix having one end connected to one end of said first helix, a rod slidably mounted in said first helix, one end of. said rod being connected to the other end of said second helix, a hook on the other end of said rod and a filamentary cathode supported by said hook.

3. In an electron discharge device, a block of insulating material having an aperture, a pair of integral axially aligned wire helices of different diameters, the smaller of said helices being arranged in said aperture, a rod slidably mounted in the smaller of said helices, one end of said rod being connected to that end of the larger helix remote from the smaller helix, a hook on the end of said rod. and a filamentary cathode supported by said hook.

In Witness whereof, I hereunto subscribe my name this 21st day of November A. D.,

PAUL M. WATROUS. 

